Contactor and separation apparatus and process of using same

ABSTRACT

An improved contactor/separator process is presented where one or more stages of contact and separation is achieved by providing one or more shroud and disengagement device combinations within a vessel, where the disengagement device is connected to the top of the shroud that contains vertically hanging fibers. A liquid admixture of immiscible fluids is directed co-currently upward through the shroud at flooding velocity or greater, where all of the admixture exits the disengagement device through a coalescing material. Tray supports are used to stack additional shroud and disengagement combinations vertically within the vessel. Each tray allows less dense liquids exiting one disengagement device from a lower shroud and disengagement device combination to enter the bottom of a shroud of a shroud and disengagement device combination position vertically above the lower shroud and disengagement device combination.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 16/825,202, filed Mar. 20, 2020, which is a divisional of U.S.patent application Ser. No. 15/869,271 filed Jan. 12, 2018, now U.S.Pat. No. 10,633,599. The entire disclosure contents of theseapplications are herewith incorporated by reference into the presentapplication.

FIELD OF INVENTION

The invention relates to a co-current up flow process and apparatus forcontacting and separating a mixture of at least two liquids havingdifferent densities in a non-dispersive process utilizing a plurality ofvertically hanging fibers contained in a shroud and disengagementdevice, where the disengagement device is connected to the top of theshroud. The process allows a hydrocarbon feed to be treated with anaqueous solution to remove acidic impurities, such as mercaptans,hydrogen sulfide, carbon dioxide, sulfur dioxide, and carbonyl sulfide.

BACKGROUND

In hydrocarbon treatment processes, it is often necessary at some pointin the process to contact and then separate two or more liquids fromeach other based on density differences. One approach is to use MerichemCompany's FIBER FILM® contactor technology in combination with ahorizontal settling vessel. These fiber-film type separators/contactorsare described in U.S. Pat. Nos. 3,758,404; 3,977,829 and 3,992,156, allof which are incorporated herein by reference. The basic design of afiber-film type contactor/separator comprises a plurality of verticalhanging fibers contained either totally or partially within a verticalshroud. This shroud is configured to maintain the liquids introduced atthe top of the shroud within the inside of the shroud and in contactwith the hanging fibers as the liquids flow downward. i.e., downwardflow that is parallel to the vertical axis of the fibers and shroud.Once the liquids exit the shroud they enter a separation section that islocated below the shroud, typically a horizontal settler, where gravityseparates the phases, with the lower density liquids forming an upperlayer and the higher density liquids forming a lower layer. Each layercan then be selectively removed from the separation section of theapparatus.

Using the above-described known contacting scheme, refiners have treatedlow density liquid hydrocarbon feeds with higher density aqueoustreating liquids, where both liquids are introduced at the top of thehanging fibers as an admixture such that gravity pulls the liquidadmixture vertically down the hanging fibers that are contained withinthe shroud. Although such contacting schemes have found some amount ofsuccess, there is room for improvement, specifically with regard toflexible process configuration that lead to cost savings in new plantconstruction and old equipment modification. The present inventionprovides such an improvement over traditional standalone down flowcontactors that require more piping, level control instruments, controlvalves, and more plot space to achieve the same functionality,especially in two-stage configurations. These and other improvements ofthe present invention will become evident from the following descriptionand accompanying drawings

SUMMARY

Our invention is directed to an improved apparatus and process forcontacting at least two immiscible liquids, where a low density feedliquid is contacted with a higher density treating solution so as toextract and remove contaminants from the low density liquid. Thiscontacting occurs as both liquids are flowing co-currently and upwardwithin a vertical shroud containing a plurality of vertically hangingfibers. Contact of the two fluids as an admixture with the fibers withinthe shroud allows for the mass transfer of contaminants from the lowerdensity liquid into the higher density treating solution. The flow rateof the admixture is preferably at or greater than the flooding velocity,which is defined as the minimal velocity at which both the organic phaseand the aqueous phase flow upward. Ultimately, the admixture reaches thetop of the shroud and exits into a disengagement device that contains acoalescing material that is designed to break any dispersion or emulsionof the two liquids. All the liquids entering the disengagement deviceexit the disengagement device following a radial flow path that isangled with respect to the vertical axis of the vessel holding theshroud and disengagement device combination. The exiting liquids enter agravity settling zone that surrounds the outside of the shroud thatallows separation of the two liquids.

In a preferred configuration, our invention includes a vessel, eithernew or existing vessel, having an interior volume that contains a shroudpositioned within the interior volume and preferably supported on a trayconfigured to direct liquid flow upward inside the shroud. Preferably,the vessel is a vertical vessel, meaning that the height of the vesselis greater than the diameter of the vessel. Most preferably, the vesselhas the same or nearly the same diameter at the top as it does at thebottom. In other words, there is no abrupt transition from an uppervertically oriented circular section to a lower circular horizontalsection. In situations where an existing apparatus is to be retrofittedaccording to our invention, the vessel could have varyinglength/diameter ratios and would likely have a number of internalcontacting stages, such as sieve trays, valve trays, or sections ofstructured packing.

In another possible embodiment of our invention, there is a shroudpositioned within the vessel that has attached to a top portion, i.e., aportion that is furthest from ground level, a disengagement device, thatoperates as a coalescer and that allows the liquids flowing co-currentlyup flow through the shroud to flow radially out of the disengagementdevice following a flow path that is tangential to the vertical axis ofthe vessel. As the liquids follow this tangential flow path all theliquids necessarily contact the coalescing material associated with thedisengagement device. The top of the disengagement device is designedand configured as a cap or cover that causes all of the liquid flowingup flow into the disengagement device from the shroud to following thetangential flow path through the coalescing material. On the inside ofthe top cover of the disengagement device a wire or rod network holdsthe fibers in place and allows the fiber to be installed or removed fromthe shroud.

At the bottom, open end of the shroud there may be another supportstructure than can attach to the fibers so that the fibers aremaintained in a vertically hanging orientation within the shroud duringthe co-current up flow of the liquids through the shroud. Preferably, aliquid distributor is located within or adjacent to the bottom open endof the shroud. The bottom of the shroud can also be positioned over atray that directs liquids up into the shroud. The tray can also act as astructural support for the shroud.

Within the shroud hangs one or more bundles of long ribbons or fibersthat define a vertical axis that is parallel to the vertical axis of thevessel. These fibers are configured to maximize contact of liquids thatare typically immiscible and consist of a higher density liquid and alower density liquid. An example of such liquids would include a liquidhydrocarbon and an aqueous treatment solution. The hanging fibers arepositioned vertically within the shroud and within the disengagementdevice roughly perpendicular to ground level. The fibers within theshroud can be a separate independent bundle or an extension of the fiberbundle that is contained within the disengagement device. Preferably,the fibers comprise long thin filaments or ribbons made of materialsselected from a group consisting of, but not limited to, metal fibers,glass fibers, polymer fibers, graphite fibers and carbon fibers thatmeet two criteria: (1) the fiber material must be preferentially wettedby the admixture of at least two immiscible liquids; and (2) the fibersmust be of a material that will not contaminate the process or bedestroyed by it, such as by corrosion.

In yet another embodiment of our invention the process can include anapparatus for contacting at least two immiscible liquids where theapparatus includes a vertical column having an interior space and avertical axis. A shroud is positioned vertically within the interiorspace parallel to the vertical axis, where the shroud comprises lengthdefined by a solid, non-porous wall extending from a bottom end to a topend. A bundle of fibers hangs vertically within the shroud parallel tothe vertical axis, where the non-porous wall contains and forces liquidsintroduced into the shroud to flow vertically upward to contact thefibers. A feed inlet is positioned adjacent to or within the bottom endof the shroud, which is preferably an open end.

A coalescer, as part of a disengagement device, is connected to, or anintegral part of, the top end of the shroud, where the coalescer isaffixed to a porous support surrounding the fibers and extendingvertically from the top end of the shroud terminating at a closed coveror cap that does not allow the liquids flowing upwards within thedisengagement device to exit the top of the disengagement device. Theclosed cover instead forces all the liquids to exit through thecoalescing material that essentially forms a wall or conduit as part ofthe disengagement device. The radial flow path of the liquids flowingthrough the coalescing material is not parallel to the vertical axis ofthe vessel. The apparatus also includes a gravity settling zone locatedat a bottom section of the interior space of vessel and above the bottomof vessel or above at a tray that connects to the bottom end of theshroud. The setting zone is an annular space around the outside of theshroud. The denser liquid that settles out in a lower layer of thesettling zone is not in liquid communication with the liquid admixtureliquid flowing upward within the shroud.

The porous support of the disengagement device allows liquid to contacta coalescing material that may be inserted within a supporting envelopehaving one or more openings. This supporting envelope can be in the formof an annulus having inner and outer walls each having one or moreopenings and where the coalescing material is positioned between theinner and outer walls adjacent to the one or more openings. Preferably,the coalescing material is selected from the group consisting of wiregrid, porous metal wall, open-celled sponge, woven wire screen, knittedwire mesh, woven or non-woven fibrous material of metal, polymer resinsor combinations of metal and polymer. Most preferably, the coalescingmaterial has an installed density of from about 15 to about 30 lb./ft³and a volumetric void fraction of from about 90% to about 99%. The oneor more openings of the support can also represent at least a 50% openarea of the coalescer.

The liquids fed to the apparatus of our invention can be as separatestreams or as an admixture of a lower density liquid containingcontaminants and a higher density treating liquid. The liquids flowupward and parallel to the vertical axis within the shroud. The walls ofthe shroud are impermeable and can be a tube-like pipe or conduit likestructure having round, oval, square, rectangular or another shape thatensures contact of the hanging fibers with the admixture of liquidsflowing upwards. The actual cross-sectional shape of the shroud is notimportant to the invention and the shroud can vary in diameter or shapeacross the vertical length of the shroud. Because the shroud has noopenings in the wall, the admixture of liquids must flow upward towardthe top of the vessel and parallel to the vertical axis. This containedflow of the admixture within the shroud ensures that the admixture ofliquids is forced to continue flowing in an upward direction parallel tothe vertical axis while contacting the bundle of hanging fibers wheremass transfer can occur such that the contaminants from the lowerdensity feed liquid are transferred to the higher density treatingliquid.

Once the admixture of liquids has reached the disengagement device atthe top of the shroud, the admixture of liquids can only exit thedisengagement device following a radial flow path that is not parallelto the vertical axis defined by the hanging fibers. As the admixture ofliquids exits the disengagement device in a radial flow path, theadmixture can encounter a top plate or wall on the disengagement devicethat tends to force the exiting admixture to flow downward in theannular area between the shroud and the vessel wall. Additionally, asthe admixture exits the disengagement device the immiscible liquids inthe admixture coalesce into separate liquid phases. Depending on theproperties of the coalesced liquid, droplets, rivulets or small steamsof the higher density liquid are formed that fall downward on theoutside of the disengagement device and the outside of the shroud inparallel to the vertical axis. The coalesced higher density liquid willflow downward through the annular area between the shroud and the vesselwall and will settle into a lower phase layer at the bottom of thevessel interior. This lower phase layer is not in fluid communicationwith the admixture entering the bottom of the shroud as it is sealed offby a connection with the bottom of the vessel or a tray. The less denseliquid in the admixture of liquids exiting the disengagement deviceforms the upper phase layer within the interior of the vessel thatdefines the gravity settling zone occupying the interior volume betweenthe outside wall of the shroud and the inside wall of the vessel. Withinthe gravity settling zone the liquids undergo further separation of thehigher density liquid from the lower density liquid with the lower phaselayer comprising the higher density liquid and the upper phase layercomprising the lower density liquid. A liquid interface is establishedwhere the two layers join. Preferably, the liquid interface is locatedat a point closer to the bottom of the shroud than to the top of theshroud. The gravity settling zone is designed to allow a sufficientresidence time to provide additional separation time and efficiency.

The disengagement device can be a separate structure connected to theshroud or it can be fabricated as a unified part of the upper portion ofthe shroud so that the disengagement device is integral with the shroud.Regardless of the specific construction, the disengagement device mustallow all of the admixture of liquids to exit radially through one ormore openings in a tangential flow path, i.e., one that is not parallelto the vertical axis of the vessel. A preferred disengagement devicecomprises a vertical segment connected to the top of the shroud eitheron the inside of the shroud or, more preferably, on the outside of theshroud. The disengagement device should have one or more side openingsor holes that allow radial flow of a portion of the admixture ofliquids. In some case the side openings are formed as a perforatedextension of the shroud. Preferably, this perforated extension can bewrapped with a wire screen or other cage-like support structure thatholds the coalescing material, which is positioned to contact theadmixture of liquids that exits radially from the disengagement devicefollowing a flow path that is roughly perpendicular or at approximatelya right angle relative to the vertical axis. The wrapped coalescingmaterial can be held in place by bands, ties, clamps or other fastenersattached to the external surface of the disengagement device providedthat the exiting admixture of liquids is forced to contact thecoalescing material.

The coalescing material is selected from the group consisting of wiregrid, porous metal wall, open-celled sponge, woven wire screen, knittedwire mesh, woven or non-woven fibrous material of metal, polymer resinsor combinations of metal and polymer resins, multiple co-wovenfilaments, packing, fiber filters, and combinations of media layer oneach other. The coalescing material can be fabricated from stainlesssteels, Duplex stainless steels, alloys, plastics, fluoropolymers,fibrous components (polyolefin, polyesters, glass fibers, and likematerials), and mixtures of same. The coalescing material is mostadvantageously positioned and/or supported as part of the disengagementdevice to interact with the admixture of liquids to cause formation ofsmall droplets. These droplets then grow to larger droplets thateventually enter the gravity settling zone whereby the heavier phase ormore dense liquid forms a lower phase that settles out and separatesfrom the lighter, less dense liquid by gravity.

Wire mesh coalescing material can comprise a combination of wires andfibers to create a maximum surface area for droplets to coalesce. Inmany cases the wire and fiber are from a different constructionmaterial, where one is hydrophilic (e.g. metal) and the other ishydrophobic (for example, polyolefin or fluoropolymer) which enhancesthe separation. Examples of such a “co-woven” materials are sold byAMACS Process Tower Internals of Alvin, Tex. There is an increasedcoalescence effect at the junction point between both materials.Therefore, using both the metal and polymeric materials will increasecoalescing efficiency significantly.

Most preferably, the coalescing material is incorporated into an annularsupporting envelope or ring that forms part of the vertical length ofthe disengagement device. Alternatively, the coalescing material itselfmaybe formed into an annulus that that is affixed to the disengagementdevice. Where the coalescing material is incorporated into an annularsupporting envelope, the inner ring or wall of the supporting envelopecontains a plurality of holes that allow the admixture of liquids topass into the inside of annulus where the admixture contacts thecoalescing material that is positioned within or otherwise packed intothe annulus. This inner wall could be the perforated extension of theshroud as mentioned above. The outer ring or wall of the annuluslikewise has a plurality of holes, slots, perforations, screen or gridopenings or other such openings to allow the admixture to pass to theoutside of the disengagement device. The type of openings used in theouter wall may or may not be the same as that used on the inner wall.Regardless of whether the coalescing material is located in a supportingenvelope having two walls with perforations, or is itself formed into anannulus without supporting walls, or is just wrapped around a singlewall that is perforated, the volumetric void fraction of the coalescingmaterial is preferably in the range of from about 90% to about 99%, morepreferably from about 95% to 98%. The coalescing material shouldpreferably occupy a volume that is sufficient to eliminate dispersionand form a coalesced liquid as either droplets or a continuous liquidstream. The amount of coalescing material needed can be varied toincrease or decrease the holdup or residence time necessary to form thecoalesced liquid. A preferred coalescing material is a co-woven typematerial comprised of 316 stainless steel and polytetrafluoroethylene(Teflon) fiber filaments, with very fine fiber size and having aninstalled density of around 15 to 30 lb/ft³.

The apparatus of our invention finds utility in a mass transfer andseparation process wherein at least two immiscible liquids, such as, butnot limited to, an admixture of an aqueous treatment solution and one ormore hydrocarbons contaminated with sulfur compounds, are contacted inorder to extract the sulfur contaminants. After the transfer of thesulfur contaminants into the aqueous treating solution, the twoimmiscible liquids are separated and removed from the gravity settlingzone. In another aspect, the invention is directed to an improved liquidhydrocarbon treatment process where sulfur contaminants are extractedfrom a hydrocarbon using an aqueous treating solution containing aliquid catalyst. The aqueous treating solution containing the extractedsulfur compounds can be subsequently directed to another process tocatalytically convert the extracted sulfur contaminants, i.e., convertmercaptans to disulfide oils (DSO) in an oxidation reaction. Ourinvention can be used in treating any hydrocarbon, including crude oil,LPG, kerosene, naphtha, natural gas condensate, gasoline or other fuels,where the interfacial tension between the hydrocarbon commodity and thetreating solution is less than 10 dynes/cm and more particularly lessthan 5 dynes/cm and where the phases tend to remain as a dispersionwhich cannot be immediately resolved and accumulates in the vessel. Theinvention achieves separation residence times many times shorter than inconventional gravity settlers.

As used herein, disulfide oil or DSO is meant to include a mixture ofpossible disulfides, including dimethyl disulfide, diethyl disulfide,methyl ethyl disulfide and higher disulfides. Likewise, the termmercaptan is meant to include any of a class of thiols that are similarto the alcohol and phenol, but containing a sulfur atom in place of theoxygen atom. Compounds containing —SH as the principal group directlyattached to carbon are named ‘thiols’.

In yet another aspect of our invention the separation process andapparatus described above finds utility in a process comprising a methodfor treating a sour hydrocarbon containing mercaptans where the liquidhydrocarbons containing mercaptans are mixed with an aqueous treatmentsolution comprising water, alkali metal hydroxide, a polyvalent chelatedmetal catalyst, and at least one alcohol, preferably having atmosphericboiling points of 65° C. to 225° C. The admixture of liquids is thendirected up flow into and through the shroud as a co-current admixture.Mass transfer of the mercaptans occurs as the admixture of liquidscontacts the vertical hanging fibers contained within the shroud to forma product admixture of immiscible liquids that is directed upward withinthe shroud, where the admixture exits the shroud and enters thedisengagement device. Ultimately the admixture travels upward within thedisengagement device where the top cap or cover causes the liquids toexit the disengagement device in a radial flow path relative to thevertical axis. The exiting liquids enter a gravity settling zone in abottom section of the interior space of vertical column surrounding theoutside of the shroud. The outside of the shroud is sealed with a trayor the bottom of the vessel to prevent liquid settling in the lowerphase of the settling zone from entering the inside of the shroud.

A hydrocarbon stream reduced in sulfur contaminants forms a top phaselayer in the settling zone, which can be removed from the processthrough a first outlet at the top of the vessel. The aqueous treatmentsolution containing the extracted mercaptans is referred to as spentsolution and forms as a lower layer and is removed from the processthrough a second outlet located in the bottom portion of the vessel.This spent treatment solution can be partially recirculated to mix withthe contaminated hydrocarbon feed to the process and the remainder canbe regenerated in a separate process. The regenerated treatment solutioncan be mixed with fresh make-up solution and then returned to mix withthe contaminated hydrocarbon feed. In the situations where the aqueoustreatment solution contains a catalyst component, then the spenttreatment solution can be further processed in the presence of oxygen tooxidize the mercaptans to DSO that can then be separated from thetreatment solution.

In another embodiment, our invention can be used as a multiple stagemethod for treating an admixture of immiscible liquids, where two ormore shroud and disengagement device combinations are supported thewithin the same vertical column and are positioned in a verticallystacked configuration one above the other. Each shroud and disengagementcombination would contain a bundle of fibers as discussed above andwould be connected to and supported by a tray mounted to the interiorwalls of the vessel. The tray contains a center pipe or passage whichdirects the lower density treated liquid from the upper phase layer ofthe gravity settling zone of the lower section into the entrance of thefiber bundle in the upper section. The aqueous treatment solution mixedwith the lower density treated liquid in the second stage can comprise arecycled portion of the lower phase of the gravity settling zone of thesecond stage as well as fresh or make-up aqueous treatment solution.

In a two-stage process a liquid feed of hydrocarbons contaminated withsulfur compounds is fed to the open end of a first shroud anddisengagement device combination along with an aqueous treatmentsolution that comprises only water and alkali metal hydroxide, i.e., acaustic solution or such a caustic solution that also includes acatalyst, such as a chelated polyvalent metal catalyst, or at least onealcohol, preferably having atmospheric boiling points of 65° C. to 225°C. The hydrocarbon and aqueous liquids form an admixture that flowsupward through the first shroud and disengagement combination positionedin the lower portion of the vessel, preferably centered within thevessel along the longitudinal axis of the vessel. As the admixturecontacts the hanging fibers the sulfur contaminants are removed from thehydrocarbon. After exiting the side openings the disengagement devicedefined liquid droplets of upgraded or sweetened hydrocarbon and defineddroplets of spent aqueous treatment solution fall into the gravitysettling zone where two liquid layers form, one being a lower layercomprising the spent aqueous treatment solution and the upper layercomprising the upgraded hydrocarbon. The aqueous lower layer exits thevessel through the annular space between the outer wall of the shroudand the inner wall of the vessel. The upgraded hydrocarbons are removedas a stream from the top of the upper layer, where it is directedthrough an opening in the above tray to the entrance of the secondstage.

The upgraded hydrocarbon removed from the first stage mixed with asecond stream of aqueous treatment solution is then introduced into asecond shroud and disengagement device combination where the admixtureformed with the hydrocarbon and an aqueous stream, separate from theaqueous stream in the first stage, contacts a second bundle of hangingfibers to remove any remaining mercaptans from the hydrocarbon that werenot removed in the lower first stage. This second stage can employ thesame type of hanging fibers, the same type of disengagement device, andgravity settling zone as the first stage. The liquids exiting thedisengagement device in the second stage are ultimately separated in asecond gravity settling zone. A treated hydrocarbon stream having evenlower contaminants than the first stage is removed from the top of thevessel and a portion of the spent aqueous treatment is removed from thecan be mixed with fresh and/or regenerated aqueous treatment solutionand a portion of the resultant admixture can be used as a portion of theaqueous treatment solution introduced and mixed with the sourhydrocarbon feed entering the first stage. Similar steps may be repeatedfor the third and fourth stages, if needed.

Regardless of the number of stages employed, the contact of theadmixture of immiscible liquids with the bundle(s) of hanging fiberscauses the fibers to be preferentially wetted by the aqueous liquid toform a thin film on the surface of fibers, and consequently presents alarge surface area for mass transfer and contact with the hydrocarbonwithout substantial dispersion of the aqueous phase in the hydrocarbon.A rapid liquid-liquid mass transfer is enabled by both the large surfacearea and the functionality of the aqueous solution, which in turnenables the contaminants to be transferred from the hydrocarbon to thethin film of the aqueous treatment solution. As mentioned, two or morestages of contacting with an aqueous treatment solution may be adoptedto achieve a greater removal of contaminants.

In those situations where the aqueous treatment solution contains acatalytic component, preferably an oxidation catalyst is used based on aliquid chelated polyvalent metal catalyst solution. Polyvalent catalystsinclude, but are not limited to, metal phthalocyanines, wherein themetal cation is selected from the group consisting of manganese (Mn),iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), ruthenium(Ru), rhodium (Rh), palladium (Pd), silver (Ag) etc. Catalystconcentration is from about 10 to about 10,000 ppm, preferably fromabout 20 to about 4000 ppm. The particular catalyst selected may beincluded during preparation of the treatment solution and/or later addedto the solution at the place of its use.

The catalytic aqueous treatment solution can also include one or morealcohols that have atmospheric boiling points of from 65° C. to 225° C.These alcohols include, but are not limited to, methanol, ethanol,1-propanol, 2-propanol, 2-methyl-1 propanol, 2-methyl-2-butanol,cyclohexanol, phenol, cresols, xylenols, hydroquinone, resorcinol,catechol, benzyl alcohol, ethylene glycol, propylene glycol, and otheralkyl phenols. When mixed with one or more alkali metal hydroxides,alkali metal salts of the alcohol are formed, preferably in aconcentration of from about 5 to about 40 wt %, most preferably fromabout 10 to about 35 wt %. One type of preferred alcohol is an aromaticalcohol, which are compounds represented by a general formula ofaryl-OH. The aryl can be phenyl, thiophenyl, indolyl, tolyl, xylyl, andalike. Preferred aromatic alcohols include phenol, cresols, xylenols,methyl ethyl phenols, ethyl phenols, trimethyl phenols, naphthols,alkylnaphthols, thiophenol s, alkylthiophenols, and similar phenolics.Non-aromatic alcohols can be primary, secondary or tertiary alcohols,including methanol, ethanol, n-propanol, iso-propanol, cyclohexanol,2-methyl-1-propanol, and 2-methyl-2-butanol. A mixture of differentalcohols can also be used. The preferred alcohols have an atmosphericboiling point of from about 80° C. to about 215° C. The preferred alkalimetal salts of alcohol include, but are not limited to, potassiumcyclohexoxide, potassium iso-propoxide, dipotassium propylene glycoxide,potassium cresylates as well as their sodium counterparts, and mixturesthereof.

In a most preferred catalytic treatment solution formulation, one ormore carboxylic acids are included. Such acids include, but are notlimited to, fatty acids, naphthenic acids, amino acids, keto acids,alpha hydroxy acids, dicarboxylic acids, and tricarboxylic acids. Theseacids also react with the alkali metal hydroxides to produce theiralkali metal salts in concentrations from about 0 to about 40 wt %,preferably from about 5 to about 25 wt %. In general, the carboxylicacids can include alkanoic acids and naphthenic acids, where thealkanoic acids are represented by R—COOH, where R is a hydrogen or analkyl group ranging from CH3- (i.e. acetic acid) to CH3(CH2)18- (i.e.arachidic acid). Naphthenic acids are a mixture of multiple cyclopentyland cyclohexyl carboxylic acids with their main fractions preferablyhaving a carbon backbone of 9 to 20 carbons. A mixture of multiplecarboxylic acid compounds can also be used as part of the treatmentsolution.

Regardless of whether a catalyst component is used, the aqueoustreatment solution can contain an alkali metal hydroxide selected fromlithium hydroxide (LiOH), sodium hydroxide (NaOH), potassium hydroxide(KOH), rubidium hydroxide (RbOH), and cesium hydroxide (CsOH). More thanone alkali metal hydroxides can be used. The alkali metal hydroxide ispresent at a concentration that is more than sufficient to ensure allalcohols and carboxylic acids to form their corresponding alkali metalsalts, if present. Sodium hydroxide and especially potassium hydroxideare preferred. In situations where catalytic conversion is not required,the treatment solution would just contain the above-mentioned alkalimetal hydroxides as the active ingredient.

Additional treatment solutions include, but are not limited to, acids,bases, amines, ionic liquids, or eutectic solvents. Examples of acidsinclude, but are not limited to, sulfuric acid, hydrochloric acid, orhydrofluoric acid can be used. Bases include, but are not limited to,alkali metal hydroxides selected from lithium hydroxide (LiOH), sodiumhydroxide (NaOH), potassium hydroxide (KOH), rubidium hydroxide (RbOH),and cesium hydroxide (CsOH). Sodium hydroxide and especially potassiumhydroxide are preferred. Amines include, but are not limited to, anycommonly used industrial amine, but especially monoethanolamine,diethanolamine, and methyl diethanolamine. Ionic liquids include commonliquid electrolytes including, but not limited to, imidazolium basedionic liquids such as 1-butyl-3-methylimidazolium chloride or1-Butyl-3-methylimidazolium hexafluorophosphate. Deep eutectic solventsinclude are a special class of ionic liquids formed from a eutecticmixture such as a mixture of a quaternary ammonium salts and a hydrogenbond donor. An example of deep eutectic solvents includes, but is notlimited to, a mixture of choline chloride and phenol.

Any number of hydrocarbon feeds with boiling point up to about 350° C.can be treated in our process using our aqueous treatment solution,including, but not limited to, crude oil, kerosene, jet fuel, diesel,light and heavy naphtha. Other feedstocks may include straight runhydrocarbons or cracked or selectively hydrotreated hydrocarbons, LPG,naphtha, crude, crude condensates, and similar materials. Still anotherpossible feedstock that can be used in the process of our inventionwould include crude oil, ranging from raw crude oil (i.e., untreated andstraight out of ground, wellhead oil) to partially or fully treatedcrudes that have been desalted, dewatered, stripped, or de-odorized andmixtures of these. These so-called “pipeline-ready” crudes or “refineryready” crude oils at the end of pipeline transportation can be used inour process as the liquid hydrocarbon feed. By the method of ourinvention, mercaptans in crude oils which have 95 wt % atmosphericequivalent boiling points of up to 600° C. are converted into disulfideoils, prior to fractionation.

Yet another aspect of our invention involves retrofitting an existingunit operation to add one or more of the shroud and disengagementcombinations described above into a vessel of the existing unitoperation. More specifically, such a retrofitting process could includeselecting a vessel that is part of the existing unit operation, wherethe vessel has a vertical axis, removing one or more structuralcomponents from within the vessel, installing a support tray or internalhead within the vessel, and installing a shroud and disengagement devicecombination vertically within the vessel such that the shroud isparallel to the vertical axis of the vessel. A bundle of fibers is alsoinstalled within both the shroud and the disengagement device such thatthe bundle of fibers hangs vertically and parallel to the vertical axis.Preferably, the disengagement device is connected to the top end of theshroud and has a porous support that extends vertically from the top endof the shroud. A closed top of the disengagement device is designed suchthat all liquids flowing inside the disengagement device must exit theporous support of the disengagement device. The flow path of the exitingliquids following a flow path is tangential to the vertical axis. Oncethe liquids exit the disengagement device they flow either upward ordownward based on the density of the liquid. During installation, thesupport tray is connected to the shroud such that liquids introducedinto the vessel flow vertically upward through the shroud and thedisengagement device contacting the fibers. In some cases, it isdesirable to retrofit an existing vessel by adding at least two shroudand disengagement device combinations in a vertically stackedconfiguration such that liquid exiting the disengagement devices of oneof the shroud and disengagement device combinations must enter theshroud of the other shroud and disengagement device combination.

Another retrofitting process could include starting with an existingfiber film contacting apparatus that was designed for downwardco-current liquid flow through a shroud containing vertical hangingfibers and converting the existing apparatus to a co-current up flowprocess. Such retrofitting method would include removing the existingshroud and attaching a disengagement device to the top end. A tray orother supporting structure would be added to the lower part of thecontacting apparatus. The retrofitted shroud containing thedisengagement device would be connected to the tray such that the shroudis parallel to the vertical axis of the contacting apparatus. Theexisting (or new) bundle of fibers is also installed within both theretrofitted shroud and the disengagement device such that the bundle offibers hangs vertically and parallel to the vertical axis. As mentionedthe disengagement device is connected to the top end of the shroud andhas a porous wall that extends vertically from the top end of theshroud. The top of the disengagement device closed such that all liquidsflowing inside the disengagement device must exit the porous wall of thedisengagement device.

One preferred method to manufacture the shroud and disengagement devicecombination is to start with a rolled, non-perforated steel sheet orplate. The lower portion of the rolled steel sheet or plate defines theshroud. The upper portion of the rolled steel sheet can be fabricated tomake the disengagement device by drilling, punching, or cutting slots tocreate one or more openings such that the upper portion has at least 50%open area and preferably with enough mechanical strength to supportitself as well as the weight of the other portions of the disengagementdevice and the force of the liquid. In another method, a wire or rodframe could be connected to the top of the shroud thus avoiding the needto drill, cut or punch openings in the rolled steel sheet. In eithermethod, a coalescing material is affixed to the upper portion, or to thewire frame, in any suitable manner, for example, by wrapping thecoalescing material in layers around the openings or to the wires.Pleating, blocking or other procedures can be used to attach thecoalescing material with the goal of having a uniform density and toleave no holes or gaps where the exiting liquid could channel throughwithout contacting the coalescing material. In the case where openingsare drilled, cut, or punched in the upper portion of the rolled steelsheet the coalescing material can be installed either to the inside orthe outside of the rolled steel sheet.

These and other embodiments of our invention will become more apparentfrom the detailed description of the preferred embodiment containedbelow.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 schematically illustrates a process flow diagram for one possibleembodiment of the invention that includes a single stage contacting andseparation apparatus; and

FIG. 2 schematically illustrates a process flow diagram for anotherpossible embodiment of the invention that includes a two-stagecontacting and separation apparatus.

FIG. 3 schematically illustrates a cross-section of a portion of thedisengagement device;

FIG. 4 schematically illustrates a top view of one embodiment of a trayseparating two or more stages within the contacting and separationapparatus; and

FIG. 5 schematically shows a side view cross-section of the trayillustrated in FIG. 4.

DETAILED DESCRIPTION

A comparison of the instant invention with an apparatus and processknown in the art is helpful in understanding the improvements in ourinvention. Prior known processes employing fiber-film type contactorsfor contacting two immiscible liquids to effect mass transfer ofcontaminants from one liquid to another typically involve downward flowof the liquids from the top of a bundle of hanging fibers. There areother types of known processes such as sieve tray countercurrentliquid-liquid extractors but these processes need to operate atrelatively low hole velocity and low overall superficial velocity in thetower because at some point the unit becomes limited by dispersed phaseflooding or downcomer backup. Even below the flood point there is avelocity at which the carry-over of the heavy (normally aqueous) liquidphase becomes unacceptable. A mesh pad coalescer can be inserted in thetop of the tower to mitigate the carryover, however, when installed in avertical vessel these coalescers have a drop-off of efficiency withincreasing velocity. Also the coalescer also takes away from usefultower volume which could be used to effect mass transfer. There is aninherent shortcoming of the prior art devices relating to the fact thatliquid-liquid mass transfer depends on interfacial area and interfacialarea is enhanced by higher relative velocities between the phases. Butto exploit good mass transfer one must inevitably run against somemaximum velocity limit where there is an unacceptable carry-over.

Contrary to what is known in the art and what one would expect, we havefound that having the liquids flow co-currently up flow through a shroudcontaining hanging fibers at velocities at or above the floodingvelocity will achieve close to an equilibrium stage in a relativelysmall tower length of from about 2 ft. to about 40 ft.

In this instance, an equilibrium stage means a section of the towerwhere the exiting hydrocarbon stream and aqueous stream are in chemicalequilibrium. Flooding velocity is the minimum velocity at which bothhydrocarbon phase and aqueous phase will flow upward. Part of theaqueous phase can settle downward, due to gravity force, through thehydrocarbon phase if fluid velocity is not above the flooding velocity.It was determined that this flooding velocity varies from 5 cm/s to 30cm/s.

In the specific case of liquid-liquid contactors having a continuouslighter phase and a dispersed heavier phase, the flooding point is thevelocity at which the gravitational forces causing the settling of thedispersed phase are overcome by the upward drag force on the dispersedphase droplets. This causes the upward flow of the droplets and theregime abruptly changes from countercurrent to co-current upflow.

One possible embodiment of our inventive process is illustratedschematically in FIG. 1 where a first higher density liquid stream 2 ais combined with a lower density liquid stream 2 b containingcontaminants to form an admixture feed 2 c that is fed to vessel 1 andthrough a liquid distributor 10 to cause the admixture to co-currentlyflow upward into a shroud 6 containing a bundle of vertical hangingfibers 5. As the admixture flows upward in the shroud the admixturecontacts a plurality or bundle of hanging fibers 5 that define avertical axis 7. Notably, vertical vessel 1 does not have a largehorizontal section located below the hanging fibers. The hanging fibers5 are contained within the shroud 6 such that it forces the admixture ofliquids to flow parallel to the vertical axis 7 up flow to contact thehanging fibers. Mass transfer of the contaminants from the lower densityliquid to the higher density liquid occurs as the admixture travelsupward inside the shroud.

As the admixture of liquids moves upward inside the shroud the twoliquids begin to separate into distinct phases. However, in thoseprocesses where the interfacial tension of the liquids is low (i.e.,below about 10 dynes/cm), there is a tendency for dispersion to occurthat leads to a poorly defined phase interface between the liquids. Inorder to counteract this tendency, a disengagement device 13 is used atthe top end portion of the shroud. The liquid admixture flows upward outof the top end of the shroud and into the disengagement device 13. Aclosed cover or cap 11 is located at the top end of the disengagementdevice and prevents the liquid admixture from exiting the top end of thedisengagement device. Instead, the liquid admixture is forced outthrough the coalescing material 20 that makes up part of thedisengagement device 13 following a flow path that is tangential to thevertical axis 7. Once the liquids exit the disengagement device, thelighter density liquid tends to flow upward, as indicated by directionalarrow 22, and the denser liquid flows downward, as indicated bydirectional arrow 21, both flowing into the interior space 30 of thevessel that defines the gravity settling zone. The denser liquidattempts to settle into bottom phase layer 8 and the less dense liquidaccumulates in the upper phase layer 9. The interface 12 between the twolayers is well defined and allows for level control through controller31.

A cross-sectional view of the disengagement device 13 is illustrated inFIG. 3 showing the bundle of hanging fibers 5 being contained within aninner wall 25 that forms an interior volume 23. The disengagement devicecan also have an inner wall 25 and an outer wall 26 that assists incontaining the coalescing material 20. Openings 14 allow the liquidadmixture to flow into and out of the coalescing material 20.

The lower density liquid in layer 9 flows upwards and is removed via afirst outlet or process line 3. The denser liquid in layer 8 flows isremoved via a second outlet or process line 4. Controller 31 can monitorand control the vertical position of liquid interface 12 by controllingthe flow rate in line 4. In some instances, an optional secondcoalescing device or coalescing material may be added near the entranceof line 3 or in line 3 to further guard against carryover of the denserliquid. The use of the disengagement device 13 directly addresses thesituation where the admixture of liquids in the process is characterizedas having low interfacial tension (IFT). Specifically, the disengagementdevice eliminates the piling up or excessive accumulation of a so-called“dispersion band” (a slow-to-separate mixture of the phases) that canultimately cause carryover of the heavier phase.

In the particular embodiment shown in FIG. 1, the disengagement device13 is fixed to and supported on the outside surface of the top portionof the shroud 6, effectively acting as an extension of the shroud. Thecoalescing material 20 is formed as an annulus. The inner and outersurfaces, 25 and 26, respectively, of the supporting envelope 24 holdsthe coalescing material in place and provides the inlet and out openings14 (see FIG. 3) to allow the liquid admixture to flowing into and out ofthe coalescing material 20, thus allowing radial flow of the admixtureof liquids that is not parallel to axis 7. As the liquids in theadmixture pass through the coalescing material 20 any dispersion presentin the admixture is collapsed to form droplets 15. These droplets 15continue to grow until they either fall through the coalescing materialor re-enter the fiber bundle or exit through the openings in the outerwall of the disengagement device. The growth of the droplets 15represents the coalescing of one of the liquids in the admixture,typically the more dense liquid. When the droplets are of the denserliquid, they grow and fall, dropping downward to ultimately become partof the liquid in layer 8. Because little or none of the dispersionsurvives the coalescing surface 20, a distinct phase interface 12 isformed between the higher density liquid in layer 8 and the lowerdensity layer 9. This eliminates carry over of the higher density liquidin overhead line 3 and allows for precise control of interface level 12.It also avoids pump cavitation and contamination which might otherwisebe caused by drawing the less dense liquid into process line 4, whichremoves the denser liquid from the vessel.

As mentioned, the improved contactor/separator of our invention can beused to treat a liquid sour hydrocarbon stream containing mercaptans(e.g., the less dense liquid in stream 2 a) where the hydrocarbons arecontacted with an aqueous treatment solution (e.g., the denser liquid instream 2 b). The admixture formed by the combination of the sourhydrocarbon with the treatment solution and the contact with thevertical hanging fibers 5 in shroud 6 results in a mass transfer of themercaptans into the treatment solution. This results in a sweetenedhydrocarbon stream being removed from layer 9 as stream 3 and a spenttreatment solution being removed from layer 8 via line 4.

Any hydrocarbon can be treated which contains acidic species such asmercaptans. Representative hydrocarbons include straight run or crackedor selectively hydrotreated, one or more of natural gas condensates,liquid petroleum gas (LPG), butanes, butenes, gasoline streams, jetfuels, kerosenes, diesels, naphthas, crude oil and the like. An examplehydrocarbon is a cracked naphtha, such as FCC naphtha or coker naphtha,boiling in the range of about 35° C. to about 230° C. Anotherhydrocarbon is kerosene/jet fuel, which has a typical boiling range ofabout 150 to about 300° C. Such hydrocarbon streams can typicallycontain one or more mercaptan compounds, such as methyl mercaptan, ethylmercaptan, n-propyl mercaptan, isopropyl mercaptan, n-butyl mercaptan,thiophenol and higher molecular weight mercaptans. The mercaptancompound is frequently represented by the symbol RSH, where R is normalor branched alkyl, or aryl. The mercaptan sulfur is present in thehydrocarbons in an amount ranging from about 20 ppm to about 4000 ppm byweight, depending on the liquid hydrocarbon stream to be treated.Specific types of mercaptans, which may be present as straight chain,branched, or both, that may be converted to disulfide material by theoxidation process of this invention will include methyl mercaptan, ethylmercaptan, propyl mercaptan, butyl mercaptan, pentyl mercaptan, hexylmercaptan, heptyl mercaptan, octyl mercaptan, nonyl mercaptan, decylmercaptan, undecyl mercaptan, dodecyl mercaptan, tridecyl mercaptan,tetradecyl mercaptan, pentadecyl mercaptan, hexadecyl mercaptan,heptadecyl mercaptan, octadecyl mercaptan, nonadecyl mercaptan, variousmercaptobenzothiazoles, hydroxy mercaptans such as mercaptoethanol,cysteine, aromatic mercaptans such as thiophenol, methyl-substitutedthiophenol isomers, ethyl-substituted thiophenol isomers,propyl-substituted thiophenol isomers, etc.

A hydrocarbon to be treated by the process of the instant invention maybe a cracked naphtha or distillate which is hydrotreated to remove someundesirable sulfur species and other heteroatoms. An undesirable sideeffect of hydrotreating is that hydrogen sulfide formed duringhydrotreating reacts with thermally-formed olefins to form mercaptans,which are referred to as reversion or recombinant mercaptans todistinguish them from the mercaptans present in the cracked naphtha ordistillate conducted to the hydrotreater. Such reversion mercaptansgenerally have a molecular weight ranging from about 90 to about 160g/mole, and generally exceed the molecular weight of the mercaptansformed during heavy oil, gas oil, and residue cracking or coking, asthese typically range in molecular weight from 48 to about 76 g/mole.The higher molecular weight of the reversion mercaptans and the branchednature of their hydrocarbon component make them more difficult to removefrom the naphtha using conventional caustic extraction.

As mentioned, the mass transfer of the sulfur contaminants from thehydrocarbon feed is preferably performed using one of two possibletreatment solutions. The first such treatment solution could contain analkali metal as the active ingredient (a so-called caustic solution) andthe second possible treatment solution could contain an additionalcatalyst component, as discussed above. In either case, a variation ofour process could include a further downstream unit operation 40, shownas an optional addition in FIG. 1. This downstream process 40 in thecase where the treatment solution contains only alkali metal as theactive ingredient, i.e., a caustic treating solution, would involve aregenerative process where the spent caustic treating solutioncontaining mercaptans is contacted with a catalyst formulation in thepresence of oxygen to oxidize the mercaptans to disulfide oils (DSO).The disulfide oils are then separated from the caustic and eventuallyused to blend with other hydrocarbon process streams. All or a portionof the regenerated caustic solution can then be recycled in stream 41back to mix with stream 2 b.

Alternatively, the treatment solution could include both caustic and aliquid form of an oxidation catalyst. In this case, the spent treatmentsolution removed via line 4 could then be sent to the downstream unitoperation 40 where oxygen is added and the mercaptans are oxidized toDSO, which are then separated from the regenerated treatment solutionand sent for further processing or blending with other hydrocarbons. Aportion or all the regenerated catalytic treatment solution could berecycled as stream 41 and introduced into stream 2 b as needed.

Another possible variant of our invention relates to a multiple stageoperation. One example of a multi-stage process is the two-stage processschematically illustrated in FIG. 2. Each stage uses a shroud anddisengagement device combination as generally described above and shownin FIG. 1. In the two-stage process variation of FIG. 2 includes asecond shroud and disengagement combination that is positionedvertically above the first shroud and disengagement combination and issupported by internal head 35. Tray 35 is designed to direct less denseliquid 3 a that exited the first disengagement device 13 a into thebottom of second shroud 6 b containing a second bundle of fibers 5 b.

Internal head 35 also is configured to direct the more dense liquidintroduced in 4a and distributor 10 b to combine with less dense liquid3 a to form an admixture that flows upward into shroud 6 b where itcontacts fibers 5 b. In order to force the aqueous phase from 4a to flowupward into the second shroud, instead of allowing it to settle downwardinto the lower contactor, the velocity of combined stream of 3 a and 4 ashould be above the flooding velocity of approximately 5-30 cm/s, thoughthis varies with the properties of the fluid. More preferably, tray 35should have an opening 36 with diameter less than that of the shroud, tofurther increase the fluid velocity while liquid 3 a is flowing fromlower contactor to the upper contactor. It is preferred that thecross-sectional area of the said opening 36 to be less than 50% of thatof the shroud, and resulting in a fluid velocity of 40-120 cm/s at theopening.

FIGS. 4 and 5 show one possible design of tray 35 and its orientationwith respect to the shroud 6 b. Support beams 51 hold and support traydeck 50 that be secured to the shroud 6 b through a bolted flange 54 andfurther supported by tray support ring 56 that is secured to the insidewall 1 a of vessel 1. An internal manway 52 is preferably included toallow for maintenance during process shutdowns. A liquid treatment inletline 55 for introducing liquid treatment solution is shown in fluidcommunication with less dense liquid 3 a moving upward from the firststage and entering shroud 6 b in the second stage.

As evident from FIG. 2, less dense liquid 3 a has already undergone afirst mass transfer process within shroud 6 a as part of the first stageof operation. The second stage mass transfer operation that occurs inshroud 6 removes contaminants that were not removed during the firststage of operation. The separated denser liquid in layer 8 b is removedvia stream 2 b and fed to the bottom of stage 1 through distributor 10 asuch that a liquid admixture is made with the less dense feed enteringthe vessel via 2 a. This admixture is directed up flow into shroud 6 acontaining fibers 5 a. A liquid level controller 32 is used to controlthe level of interface 12 b in the second stage gravity settling zonethrough control of the removal rate of the denser liquid from layer 8 b.The less dense liquid above interface 12 b exits the vessel throughprocess line 3 b.

The denser liquid accumulating in layer 8 a of the first stage gravitysettling zone is removed via line 4 b. The amount of the denser liquidremoved is controlled by controller 31 which also monitors and controlsthe level of interface 12 a. As similarly described above for the singlestage process, an optional unit operation 40 can be included be includedas a downstream process. Likewise, as discussed above the denser liquidtreatment solution could be one of the two types previously mentionedand the regenerated treatment solution in stream 41 could be introducedinto the process through stream 4 a and/or added to stream 2 b.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the invention that others can, by applyingcurrent knowledge, readily modify and/or adapt for various applicationsuch specific embodiments without departing from the generic concept,and therefore such adaptations and modifications are intended to becomprehended within the meaning and range of equivalents of thedisclosed embodiments. It is to be understood that the phraseology orterminology herein is for the purpose of description and not oflimitation.

The means, materials, and steps for carrying out various disclosedfunctions may take a variety of alternative forms without departing fromthe invention. Thus, the expressions “means to . . . ” and “means for .. . ”, or any method step language as may be found in the specificationabove or the claims below, followed by a functional statement, areintended to define and cover whatever structural, physical, chemical orelectrical element or structure, or whatever method step, which may nowor in the future exist which carries out the recited function, whetheror not precisely equivalent to the embodiment or embodiments disclosedin the specification above, i.e., other means or steps for carrying outthe same function can be used; and it is intended that such expressionsbe given their broadest interpretation within the terms of the followingclaims.

The invention claimed is:
 1. A method of retrofitting an existing unitoperation comprising: selecting a vessel that is part of the existingunit operation, where the vessel has a vertical axis; removingstructural components from within the vessel; installing a support traywithin the vessel; installing a shroud and disengagement devicecombination vertically within the vessel parallel to the vertical axis,where the shroud has a length defined by a non-porous wall extendingfrom the bottom end to a top end; and installing a bundle of fiberswithin the shroud and the disengagement device such that the bundle offibers hangs vertically and parallel to the vertical axis, wherein thedisengagement device, is connected to the top end of the shroud; has aporous wall that extends vertically from the top end of the shroud; andhas a closed top configured to cause all liquids flowing inside thedisengagement device to exit the porous wall following a flow path thatis initially tangential to the vertical axis, wherein the support trayis connected to the shroud such that liquids introduced into the vesselflow vertically upward through the shroud and the disengagement devicecontacting the fibers.
 2. The method of claim 1, where the disengagementdevice comprises a coalescer.
 3. The method of claim 1, where at leasttwo shroud and disengagement device combinations are added to the vesselin a vertically stacked configuration such that liquid exiting the lowerof the shroud and disengagement device combinations must enter the upperof the other shroud and disengagement device combination.
 4. The methodof claim 2 where the coalescer comprises a coalescing material that ispositioned within into a supporting envelope having one or moreopenings.
 5. The method of claim 4 where the supporting envelopecomprises an annulus having inner and outer walls each having one ormore openings and the coalescing material is positioned between theinner and outer walls adjacent to the one or more openings.
 6. Themethod of claim 5 where the coalescing material is selected from thegroup consisting of wire grid, porous metal wall, open-celled sponge,woven wire screen, knitted wire mesh, woven or non-woven fibrousmaterial of metal, polymer resins or combinations of metal and polymer.7. The method of claim 4 where the coalescing material has an installeddensity of from about 15 to about 30 lb/ft3.
 8. The method of claim 4where the coalescing material has a volumetric void fraction of fromabout 90% to about 99%.
 9. The method of claim 5 where the one or moreopenings represent at least a 50% open area of the disengagement device.